Can anyone figure why one 4K movie plays, the other buffers out of control

[TeknoJunky]

[INFO] Plex, 4k, transcoding, and you - aka the rules of 4k

NOTE: for 2022 – Plex has come a long way since this FAQ was originally written, HW transcoding has become more available and more stable, and tone mapping was recently added to address the hdr/sdr color conversion issues. The first 4 ‘rules’ generally are no longer as important as they once were, but may still be a good thing to bear in mind. Dolby Vision, is an entirely other mess. THIS thread/FAQ is NOT about DV. DV work is still in progress, and there are no perfect TV’s or external devic…